起重机作业人员无证上岗，作业人员应承担法律责任。

Each nation has many volunteers(志愿者) who help to take care of others. They      books to the people in hospitals or homes for the aged. Sometimes they just visit them and play games with them or listen to their    .

Other young volunteers go and work in the homes of people who are sick or     . They paint, clean up,      their houses or do their shopping.

For boys who no longer have    , there is an organization called Big Brothers. College students and other men take these boys to baseball games or fishing places and help them to get to know things that boys      learn from their fathers.

Each city has a number of clubs     boys and girls can go to play games or learn crafts (工艺). Some of these clubs organize short trips to the mountains, beaches, or other places of interest     . Most of these clubs use high school and college students as volunteers because they are young enough to      the names of boys and girls.

Volunteers believe that the happiest people in the world are those who help to     i happiness to others.

如图所示，实线为不知方向的三条电场线，从电场中的M点以相同的速度飞出a、b两带电粒子，a、b的运动轨迹如图中虚线所示，且a、b只受电场力作用，则（　　）

A．a一定带正电，b一定带负电

B．两个粒子的加速度均减小

C．电场力对a粒子做负功，对b粒子做正功

D．两个粒子的电势能都减小

含T细胞百分率最高的部位是

A．胸腺

B．脾脏

C．淋巴结

D．扁桃体

E．外周血

在全面建设社会主义和谐社会的伟大历史进程中，我们必须高度重视哲学社会科学的作用。这是因为（）

A.哲学是世界观和方法论的统一

B.哲学社会科学是人类社会存在和发展的基础

C.哲学社会科学能够为人们提供解决实际问题的具体方案

D.哲学社会科学影响着一个国家和民族的前进方向

晚唐体诗人中身份迥异的是（）。